Refrigerator evaporator



March 1956 E. T. MORTON REFRIGERATOR EVAPORATOR 3 Sheets-Sheet 1 Filed Oct. 9, 1951 I INVENTOR.

E. T. MORTON REFRIGERATOR EVAPORATOR 5 Sheets-Sheet 2 INVENTOR. El/av/n T K721 r-fun March 13, 1956 Filed Oct. 9, 1951 FIG-.5

FIG. 4-

March 13, 1956 E. 'r. MORTON 2,737,785

REFRIGERATOR EVAPORATOR Filed Oct. 9, 1951 3 Sheets-Sheet 3 FIG. 7

1/ /7 FIG. 6

INVEN TOR.

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United States Patent REFRIGERATOR EVAPORATOR Eva'ris T. Morton, Galesburg, Ill., assignor to Admiral Corporation, Chicago',xlll., a corporation of Delaware Application October 9, 1951, Serial No. 250,396 'Claims; (Cl; 62-126) Still another expedient utilizes an ordinary type of householdirefrigerator and provides for an automatic defrosting cycle when the frost on the evaporator coils ismelted either by artificially heating the coils or by simply preventing further circulation of the refrigerant until the frost is all melted. These latter devices may; operate on a timecycle (once every twenty-four hours or the like) or may be controlled by some device which senses the formation of a certain amount of frost. Both have certain inherent disadvantages well known in the art.

My invention is concerned with the latter described expedient, and particularly with an evaporator foruse in a refrigerator chest and especially adapted for artificial heating to melt the frost off the coils in response to a control device whichmay be one of the many-well-known expedients including a clock, a frost-sensing device or a manual control; By my invention I provide a quickacting defrosting device capable of quickremoval of all frost from the evaporator such that frozen foods donot have an opportunity to thaw out. Space is provided, by the unique shape of my evaporator, for storage of open trays while defrosting without danger of condensate-- or melted frost dropping into the tray; By its shape and arrangement, a more efficient accumulator and separator of refrigerant vapors from liquid refrigerant is also pro vided.

Many other benefits and advantages of my invention will become-apparent from: the following description and accompanying figures which form a part of this. specification.

Irr the drawings: i

Fig. 1 is a' perspective view from the rear of. an evapo rator embodying. my invention;

Fig. 2 is aflfront elevational view of the evaporator;-

Fig. 3' is a top plan view thereof;

Fig. 4 is a bottom plan view heater element in place;

Fig. 5 isa. partial sectional view along line. 5-5 of Fig. 2;.

Fig. 6 is a developed plan view of the evaporator showing the paths of-flow of the refrigerant.

Fig. 7 is. a sectional. view alongline 7-7 of Fig. 4;.

Fig. 8 a partial. sectional view along line 8-8 of Fig. 3;-

thereof showing the Patented Mar. 13, 1956 Fig. 10' is a schematic view of a refrigerator system including, my improved evaporator and defroster. Briefly, my invention comprises an evaporatorv for a household refrigerator, which evaporator is formed and arranged to provide for more etficient defrosting, whether automatic or manually controlled, better evaporation and more complete separation of vapor and liquid in the return line to the compressor. The evaporator isarranged with a cold. shelf having no refrigerant tubes above itso that open trays may be placed on. the shelf in close thermal contact therewith and no condensate or melted frost will be dropped into the trays duringthe defrosting phase. The refrigerant path is through a series-parallel system of pipes conveniently makingeight passes approximately half-way around the evaporator. Each pass may have three tubes.v It will be appreciated, however, that there may be more or less than eight passes, and that each of the passes may include one or more tubes. The headers at the bottom of the evaporator for these tubes are formed withsurnps for the collection of liquid refrigerant as it condenses in the pipe. A heating element is disposed in. contact along these sumps, and to defrost, it heats the condensed refrigerant inthe sump which evaporates and circulates through the tubes where it gives up its heat of vaporization, condenses and runs back to the sumps, during this cycle-acting as artrue secondary type of system and melting the frost. The accumulator for vaporized refrigerant is conveniently built into the top of the evaporator along, with a header chamber in which. the vapors are further separatedfrom liquid, thus easing the load on the compressor unit.

More specifically, and with referenceto the drawings, my evaporator comprises two sheets 10 and 11 of metal stamped to shape and ,then spot or seam welded together by the usual process to form passageways for therefrigerant.

As best shown in Fig. 6, the passages extend from an inlet 12 through a small manifolding passage 13 to aset of one or more parallel passageways o1- tubes 14 extending outwardly. It will be apparent from the other figures that the inlet 12 and first manifold 13 are on the top of the evaporator, and that the first tubes extend around one side to the bottom of the evaporaor where they empty into a first sump manifold 15. This manifold is quite large for a purpose to be made clear hereinafter. From this manifold, three more parallel tubes or passageways 16 extend back up around the side of the evaporator in spaced parallel relation to the first three tubes14. to another upper manifold 17. It will be noted (Fig. 1) that on the. side and bottom of the evaporator, the passageways are formed only-in the outer sheet 10- of. the two sheets which make up the evaporator, while at the top thepassageways are formed in the innersheet 11. This formation preserves a flat surface both at the bottom and at the top horizontal surfaces on which open trays of water for ice cubes or with material to be frozen or preserved in a frozen state may be placed.

From the upper manifold 17 another set of .three tubes 18 extends around the sides to the bottom of the evaporator and joins a second sump manifold ,15 exactly like the first. From thence a fourth group of three tubes 19 extends back parallel to the first three sets. These latter tubes 19, however, go completely over the top of the evaporator and down the opposite side to a third sump manifold 15' similar to the first two. From here the sets of tubes 20 and 21 continue in a path back and forth a meansfor increasing its heat transferpand.

between sump manifolds l5 and an upper manifold 17 in the-*samemanner as on the first described side.

The final set of three tubes 22 extends into an accumulator 23- formed in both sheets 10 and 11 of the evapora tor. This accumulator is in the form of a large tubehav ing-1 thegtub'es- 22 coming. into one end thereof. and a=plurality of exit tubes 24, extending outward from the other end. The refrigerant, by the time it reaches this point, consists of a liquid and gas mixture. Due to the decrease 1n velocity. the liquid carried by the gas falls because of gravity. The small particles of liquid carried to this point by the gas refrigerant will collect on the walls of the accumulator 23 and will evaporate therefrom and be carried throu h the tubes 24 into the header chamber 25 which augments the action of the accumulator and further separates the liquid from the gas refrigerant. in each of the accumulator and header chambers the velocity of the refri erant is considerably reduced. and therefore, there is little or no entrainment of any liquid in the vapor as it passes hrough the chambers. From the header chamber 25. the vapor returns to the compressor 40, Fig. 10, through an exit 26 via conduit 41.

It will be noted (Figs. 1 and 2) that the evaporator in its front elevation is shaped in the form of two contiguous four-sided fi ures. one of which is greater than the other in its vertical dimension. The lower surfaces are substantially flu h with each other. There is, h wever. a step 28 formed between the up er surfaces. This whole formation is carried out by bendinrz the evapor tor from the blank or developed sh ne shown in Fig. 6. The accumulator lies ri ht on the rising part of the sten 2S, and the header chamber is above it on the hitzher of the up er surfaces. It ma also be noted that the u er surface at b th levels is flat and the tubes or na sace avs are formed in the inner metal sheet 11. Th s r des. particularly on the lower of the two stepped surfaces, a convenient c ld shelf for the freezing of ice cubes. sherbet or the like. in o en trays ith no refri erant tubes abo e he open trays from which condensate or frost could drip into the tray. The rearmost tube of the oroun 22 ma be formed in part in the outer sheet to provide sto s 29 for the tray.

It will be obvious to those skilled in the art from the above description. that this evaporator is in the nature of a dr type eva orator. This is almost complet y true during the pumping cycle of the compress r wh le the refrigerant is being circulated. However. d rin the offcycle. considerable refrigerant condenses within the tu es and drains down into the sump manifolds 15. To facilitate this. the bottom tubes all .slone sli htly toward the sumns. wh ch always have liquid therein.

After the evaporator is bent to the shape shown in Fig. 2 from the flat blank. the b ttom ed es adi cent the sum manifolds are ioined together b later l braces 30 (Fi 11 s ot we ded or otherwise fastened to the edges. Th s helps to ho d the evaporator in shape. as well as providing a convenient means for attaching an auxiliary heater as will be described.

The heater is in the form of a Ushaped element 32 lying with each of its le s alon side two adiacent sump manifolds 15. It is held in intimate contact with these manifolds bv clio devices 33 (F g. 7) fastened to the lateral straps 30 b screws 34 or o her convenient fastener. The heater i preferably an e ectrical device connected to a suitable source of electrical po er thr u h a s stem of automatically or manually controlled switches. not shown. The effec iveness of the heater may be increased by increasing the area of c n act between the heater element 32 and the sum manifolds 15. It is important therefore that these manifolds be formed with a fillet of a radius approximately that of the tube of the element 32.

Another way of increasing the contact, as shown in Fig. 9, is to surround the element with a layer or two of crinkly aluminum foil 35 or the like before fastening it in place. When the heater then is fixed into place, the foil is crushed between the heater element 32 and the evaporator walls. This crushing causes a metal-to-metal contact over a greater area than would be present in the surfaces of the two units, and therefore increases the heat transfer between them.

This heater is effective to hasten the defrosting process and may, as stated, be automatically or manually controlled. It is also contemplated that an aluting compound of good heat transfer properties, such as metallic perma gum, be used to increase the heat transferring ability by placing a quantity around the heater element at the place where it contacts the sump.

By a suitable system, the heater can be controlled so that it is turned on only when the compressor is not runnina. Such a system is well within the ability of those skilled in the art. At those times during the off-cycle, the liquid refrigerant drains into the sumps 15 which are normally full of liquid. When the heater is turned on. it causes this liquid to vaporize and further causes a circulation of the warmed vapor throughout the evaporator. heating all the tubes quickly to a temperature above the freezing point of the frost, which quickly melts off and is caught in a drip tray as is well known in the art. Thus, by utilizing the sumps to collect the liquid where it can be heated easily and turned into a warmed vapor which circulates more easily. a much quicker defrosting is accomplished. Moreover, by having all of the liquid drain into the sumps and by utilizing the accumulator and header chamber. a vapor is returned to the sump almost entirely free of li uid. When heat is applied to the sumps, each pair of which is connected to opposite or meeting ends of the evaporator. the liquid in all of the sumps is vaporized at a proximately the s me time. Therefore. it spreads outwardly and upwardly through the tubes where it ives up its lateral heat of vaporization to the tubes and the surrounding walls in such a manner that the frost is melted from the entire unit uniformly throughout nearly all of the surfaces. The condensed refri erant runs back into the sumps where it is again va orized. and the process is continued until the rise in temperature of the unit is such that all of the frost has melted. Preferably. a thermostat placed adiacent the unit at a oint where the greate t frost accumulates. operates at this time to discontinue the current to the heater. As previously stated. his

acion is of the true secondary ty e. The fr st on the tubes acts as the condenser for the s stem. and the heater the material from which the heat is abst acted. It will also be noted that. durin the re ular refri er tion c cle, the evapora or acts as a dry evaporator with the porti ns series parallel fed; whereas. during the defrosting cvcle without any change, the unit acts as a secondary refrigeration system.

In Fig. 10 T have shown schematica ly a refri eration svstem in wh ch my invention may be used. In th s case, there is provided a compressor 40 havin o e side connected b a suction tube 41 to the outlet 26 of the evaporator. The high pressure side of the compressor discharges to the condenser 42 which is connected by a capillary tube 43 to the inlet 12 of the eva orator. Current from the one side of the line 44 is applied to the compressor motor and heater. The other side of the line goes to a switch 45 which may be controlled by a thermostat 46 placed at the point where the most frost accumulates. The thermostat may be of the usual bulb tyne connected by the tube 47 into the sw tch where the usual bellows controls the movable switch blade. Normally. the thermostat 46 is sensitive only to a hi h temperature such as is obtained after the ice is melted from the evaporator. The switch 45 may be of the over center type provided with a control button 48 which. when depressed. causes a circuit to be made from the side 44' throu h the line 49 heater element 32 back through line 50 to line 44. At this time, current is supplied to the heater and the defrosting action takes place.

When the temperature of the evaporator rises to the point where all of the ice has melted, which occurs very rapidly, the thermostat operates the switch 45 to throw it back to normal position where current passes from the side 44' of the line through the line 51 to the temper ature control switch 52 and thence through the line 53 ear-sans tor'theacompressor motor. and backzsto the"line r'44,,completingith'e eircuit.

The? switch 52 controlled: by a 1 thermostat including a bulb 55 and tube 56 placed ata point wheretheitemperature will control the temperature in? the refrigerator commonly called a*cold control.

It .willbe appreciated: that my inventionisus'eful in other combinations: than that showniof which thereare many knownto the art. For instance,-the push button .or manual control" may be replaced with" aclock which Will operatetheswitch atkpredetermined time intervals. In; lieu of the clockglmcchanism responsive" to. the number cycles of refrigeration may: be used or one of thesmany types-of frost feeling devices: may bewusedi. operated by the door, why: other well known meansx By the-:stepp'ed form of the topv of the evaporator, a 'drip'free-freezer shelf is provided, and. a centrally located accumulator and headerchamber formed in" the "evaporator itself becomes feasible;

It WiH 'be ObYiOUSQtO those'sk illed in the art" that the evaporator need not be' formed; in' exactly the formdescribed,-but thatthe basic idea ofcausing the evaporation to. act'- as a secondary type refrigerationisystem" by collecting a liquidrrefrigerant in a sump in an evaporator, and heating the liquid to causeit to'vaporize and circulate the warm :vapor throughout thetubes, could be'applied' to many'forms'of evaporator. The only requisitefor this action is the provision, in the evaporator of the sump manifoldsat the lowest part of the tube system'toprovide a supply of liquid, and a heater inxheat transfer relationship" to the sumps, to heat. the collectedv liquid. The other improvements in the shape ancl'formation rof v my evaporator are refinements thereto and are not essential to the functioning of the defrosting-system. I

' Having thus described my invention, I am aware that numerous and extensive departures maybe made therefrom without departing' from the spiritor scope of: my invention.

I claim:

1. An evaporator'fora' refrigerator comprising aseries of refrigerant carrying tubes substantially enclosing a freezing compartment, the top of said compartmentbeing of stepped formation, thereby providing-a cold, drip'free shelf for open trays on the lower stepof the steppedformation, and accumulator means to: collect and return any liquid refrigerant-to said tubes connected to at least one; ofLsaidi tubes at its outlet,v said accumulator 'means being formed at the risingipartiof said stepped formation.

2: An evaporator for a refrigeratorcomprising a series of refrigerant carrying tubes substantially enclosing. a freezing compartment, the top of said compartment being of stepped formation, thereby providing a cold, drip free shelf for open trays on the lower step of the stepped formation, accumulator means to separate liquid refrigerant from gaseous refrigerant and to collect and return liquid refrigerant to said tubes connected to at least one of said tubes at the outlet thereof, said accumulator means being formed at the rising part of said stepped formation, and header means formed on the upper part of said stepped formation being connected to said accumulator means by connecting tube means and operable to assist said accumulator in separating liquid refrigerant from gaseous refrigerant.

3. An evaporator for a refrigerator comprising a series of refrigerant carrying tubes substantially enclosing a freezing compartment, the top of said compartment being of stepped formation, thereby providing a cold, drip free shelf for open trays on the lower step of the stepped formation, accumulator means to separate liquid refrigerant from gaseous refrigerant and to collect and return liquid refrigerant to said tubes connected to at least one of said tubes at the outlet thereof, said accumulator means being formed at the rising part of said stepped formation, and header means formed on the upper part of said stepped formation being connected to said accumulator means: by connecting tubemeans and operable to assist. said accumulator iin separating liquid refrigerant fromgaseous: refrigerant, said connecting tube means 5- beingdisplaced from said outlett'oprevent a straight through path for the refrigerant.-

4. An evaporator for a: refrigerator comprising refrigerant tubes substantially enclosing a freezing compartment, said tubes being connected'together as'a plurality of parallel connected groups of tubes-said. groups being; connected in series through a plurality of manifolds, afirst of said groups extending from" an inlet manifold around said compartment toa first sump manifold onsthe bottom of said; compartment, a second group extendingv from said sump: manifold in parallelv spaced relation back to'the first upper manifold atop' said compartment, a third group extending from said upper'manifold' to. a second sump manifold on the bottom of saidcompartment, a fourth group extending from said second sump manifold completely around said-compartment to. a third sump-manifold adjacent said second sump'manifold, afifth: group of tubesextendingfrom saidthird: sump. manifold to a second upper manifold, adjacent said firstlupper. manifold,-a sixth group of tubes extending from said second upper manifold to a fourth sump manifold adjacent said first sumpmanifold and a seventh group of tubes extending fromsaid fourth sump manifold to an accumulator manifold means, and outletmeans from said accumulator means to conductthe refrigerant away from said evaporator.

5. Ancvaporator for a refrigerator comprising refrigerant tubes substantially:enclosing a' freezingcompartment, said tubes beingconnected together as a plurality of parallelconnccted. groupszoftubes; said groups being connected in seriesthrough a; plurality of manifolds, a first of Said groups extending from an inlet manifold around said compartment to a first sump manifold on the bottom of said=compartment,a second group extending from said sump manifold inparallel spaced relation back to the first upper manifold atopsaid'compartment, a third group extendingfrom said'npper manifold to a second sump manifold on the bottom of said compartment, a fourth group extending from said second sump manifold completely around said compartment to a third. sumpv manifold adjacent said second sump manifold, afifth group: of tubes extending from said thirdsumprmanifoldto a second upper manifold, adjacent said first uppermanifoltha sixth group of tubes extending from said secondupper manifold to a fourth sump-manifold adjacentsaid first sump manifold and a seventh group oftubes extending from said fourth sump manifoldto an accumulator manifold means, and outlet means from said accumulator means to conduct the refrigerant away from said evaporator, and heater means in heat transferring relationship to said sump manifolds adapted to heat said manifolds intermittently and thereby cause defrosting of said evaporator.

6. An evaporator for a refrigerator comprising sheet means substantially surrounding a freezing compartment, said sheet means having two opposite edges closely adjacent cach other at the bottom of said compartment, bracing means connected between said edges, tube means formed in said sheet means adapted to carry a refrigerant in a sinuous path throughout said sheet means, sump means formed in said sheet means adjacent said edges and connected to said tube means, said sump means being adapted to collect liquid refrigerant from said tube mean heater means in heat transferring relationship to said sump means adapted to heat said liquid refrigerant intermittently to cause it to evaporate and circulate in said tube means thereby defrosting said evaporator, and clamping means attached to said bracing means to hold said heater in place. v

7. An evaporator comprised of a heat conducting body having a substantially upper continuous horizontal surface and integral vertically extending sides and lower horizontal surfaces extending inward from the sides with the innermost edges in closely spaced relation to each other and with the portion adjacent the terminating part at a lower elevation than the remaining part, said evaporator being provided with refrigerant ducts distributed about the aforesaid surfaces including sumps adjacent the edges in said lower portions, ducts extending from said sumps across the lower portion and up the vertical side and across the top toward each other, most of said ducts terminating in headers at the upper surface near the medial portion.

8. An evaporator comprised of a heat conducting body having upper continuous horizontal surfaces and integral vertically extending sides and lower horizontal surfaces extending inward from the sides with the innermost edges in closely spaced relation to each other and with the portion adjacent the terminating part at a lower ele vation than the remaining part, said evaporator being provided with refrigerant ducts distributed about the aforesaid surfaces including sumps adjacent the edges in said lower portions, ducts extending from said sumps across the lower portions and up the vertical side and across the top toward each other most of said ducts terminating in headers at the upper surfaces near the media portion, a liquid refrigerant in said evaporator in sufficient quantity to maintain said sumps in a flooded condition and heater means secured in heat transfer relation to said sumps for heating and vaporizing the refrigerant in the sumps, said evaporator arranged to condense said vaporized refrigerant and conduct the liquid refrigerant back to said sumps the latent heat of vaporization causing the walls of the evaporator to be heated.

9. An evaporator comprised of a heat conducting body having upper continuous horizontal surfaces and integral vertically extending sides and lower horizontal surfaces extending inward from the sides with the innermost edges in closely spaced relation to each other and with the portion adjacent the terminating part at a lower elevation than the remaining part, said evaporator being provided with refrigerant ducts distributed about the aforesaid surfaces including sumps adjacent the edges .in said lower portions, ducts extending from said sumps across the lower portion and up the vertical side and across the top toward each other, most of said ducts terminating in headers at the upper surface near the medial portion, a liquid refrigerant in said evaporator in sufficient quantity to maintain said sumps in a flooded conditions and heater means secured in heat transfer relation to said sumps for heating and vaporizing the rerigerant in the sumps, said evaporator arranged to condense said vaporized refrigerant and conduct the liquid refrigerant back to said sumps, the latent heat of vaporization causing the walls of the evaporator to be heated, and thermostatic means in heat transfer relation to the evaporator to control the operation of said heater means.

10. An evaporator for a refrigerator comprising refrigerant tubes substantially enclosing a rectangular freezing compartment being formed with top, side and bottom sections, said tubes being connected together as a plurality of parallel connected groups of tubes, said groups being connected in series through a plurality of manifolds, a first of sai groups extending from an inlet manifold around said compartment to a first sump manfold on the bottom of said compartment, a second group extending from said sump manifold in parallel spaced relation back to the first upper manifold atop said compartment, a third group extending from said upper manifold to a second sump manifold on the bottom of said compartment, a fourth group extending from said second sump manifold completely around said compartment to a third sump manifold adjacent said second sump manifold, a fifth group of tubes extending from said third sump manifold to a second upper manifold, adjacent said first upper manifold, a sixth group of tubes extending from said second upper manifold to a fourth sump manifold adjacent said first sump manifold, and a seventh group of tubes extending from said fourth sump manifold to an accumulator manifold means, said parallel groups of tubes being parallel to the longitudinal axis of said compartment on the top and bottom sections, and perpendicular to said axis on the side sections of said compartment, and outlet means from said accumulator means to conduct the refrigerant away from said evaporator.

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